all over the world. The US can conduct legitimate military maneunver within its ally's territory whenever it wants. Since the US has final say on military decisions in both S. Korea and Japan army, the US has problem to receive "invitation" from either country to conduct "Joint" military maneunver within their territories or international water near them.
China, on the other hand, has no military base in any of its allies. I don't think that any of the Chinese allies is comfortable to see the presence of Chinese army in their lands unless they are there for special missions.